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Commit fab89223 authored by Alan Cox's avatar Alan Cox Committed by Linus Torvalds
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vt: Add a note on the historical abuse of CLOCK_TICK_RATE 



This is one area where we can't just magic away the bizarre use of
CLOCK_TICK_RATE as it leaks to user space APIs. It also means the visible
CLOCK_TICK_RATE is frozen for architectures which is horrible.

We need to fix this somehow

Signed-off-by: default avatarAlan Cox <alan@linux.intel.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 413f81eb

drivers/char/vt_ioctl.c

+6 −0
Original line number Diff line number Diff line
@@ -400,6 +400,9 @@ int vt_ioctl(struct tty_struct *tty, struct file * file, 
	case KIOCSOUND:

		if (!perm)

			goto eperm;

		/* FIXME: This is an old broken API but we need to keep it

		   supported and somehow separate the historic advertised

		   tick rate from any real one */

		if (arg)

			arg = CLOCK_TICK_RATE / arg;

		kd_mksound(arg, 0);
@@ -417,6 +420,9 @@ int vt_ioctl(struct tty_struct *tty, struct file * file, 
		 */

		ticks = HZ * ((arg >> 16) & 0xffff) / 1000;

		count = ticks ? (arg & 0xffff) : 0;

		/* FIXME: This is an old broken API but we need to keep it

		   supported and somehow separate the historic advertised

		   tick rate from any real one */

		if (count)

			count = CLOCK_TICK_RATE / count;

		kd_mksound(count, ticks);